Advanced cladid crinoids from the Middle Mississippian of the east-central United States: primitive-grade calyces

Abstract

Species of the late Osagean and early Meramecian advanced cladid crinoid genera (suborder Poteriocrinina)Armenocrinus, Bollandocrinus, Corythocrinus, Cosmetocrinus, Culmicrinus, Cydrocrinus, Histocrinus, Hypselocrinus, Lebetocrinus, Ophiurocrinus, Poteriocrinites, Scytalocrinus, Springericrinus, andUlrichicrinusfrom Illinois, Indiana, Iowa, and Missouri are redescribed and redefined from study of type material. Nomenclatural and systematic acts include the following: 1)Poteriocrinus tenuidactylusWorthen, 1882, is a senior synonym ofScaphiocrinus obscurusWachsmuth and Springer, 1886, and is assigned toArmenocrinus; 2)P. verusMiller and Gurley, 1890, is assigned toCulmicrinus; 3)P. mammaeformisWortheninMiller, 1889, is questionably assigned toCulmicrinus; 4)Cydrocrinus coxanus(Worthen, 1882) is a junior synonym ofC. concinnus(Meek and Worthen, 1870); 5)Decadocrinus stellatusLane and Howell, 1986, is questionably assigned toHistocrinus; 6)P. crawfordsvillensisMiller and Gurley, 1890, is a junior synonym ofHypselocrinus hoveyi(WortheninWorthen and Meek, 1875); 7)Hypselocrinus boonvillensis(Miller, 1891) andH. neglectus(Miller and Gurley, 1896) are junior synonyms ofH. arcanus(Miller and Gurley, 1890); 8)Hypselocrinus vansantin. sp. is described; 9)Hypselocrinus indianensis(Meek and Worthen, 1865) is a nomem dubium; 10)Poteriocrinus arachnaeformisWorthen, 1882, is a valid species ofPoteriocrinites; 11)P. cantonensisMiller and Gurley, 1890, is assigned toScytalocrinus; 12)Ulrichicrinus coryphaeus(Miller, 1891),P. amoenusMiller, 1891, andP. brittsiMiller, 1891, are junior synonyms ofU. agnatus(Miller, 1891); and 13)P. illinoisensisWorthen, 1882, is questionably assigned toUlrichicrinus.Bollandocrinus? sp. from the Keokuk Limestone might represent the first report of the genus from North America, being previously known only from the lower Carboniferous of Great Britain.Ophiurocrinussp. from the Keokuk Limestone is the first report of this genus from the Osagean, being previously known only from the Chesterian of North America and the upper Carboniferous of Europe.